And in not doing so, he's setting a precedent for secrecy that others will likely follow.

The writing has been on the wall for months now, but Sunday seemed to make it official: Donald Trump will become the first presidential nominee since Gerald Ford to not release his tax returns during the campaign.

Both Trump’s vice presidential nominee, Indiana Gov. Mike Pence, and his campaign manager, Kellyanne Conway, essentially confirmed during their respective interviews that no disclosure would be forthcoming.

“I think as soon as the audit is completed [he will make them public],” Pence said on NBC’s “Meet the Press.” When host Chuck Todd mentioned that the most recent returns weren’t under audit, Pence didn’t blink.

“He will release all his tax returns when the final audit is completed,” Pence said.

Conway stuck to a similar script when discussing the tax returns during an interview with ABC’s “This Week.”

“Not until our accountants and our lawyers say that we should,” she said, when asked if they would be released before the election. “We’re under audit. But he has disclosed a 104-page financial disclosure form that is publicly available. Anybody can pull it up and I say that they should.”

Trump has been under constant pressure to make his tax returns public, both because not doing so would be a sharp break from prior practice and because there are a number of questions surrounding his finances and charitable giving. The latest questions were raised in a Washington Post article Saturday, which reported that, despite routine public boasting about his generosity, there was almost no evidence that Trump has given to charity since 2009.

Trump and his campaign have cited a rolling audit of his finances as the reason why he can’t disclose his tax returns. Though lawyers advise against putting out returns during an audit, they have also stressed that there is no legal prohibition from doing so.

Explanations aside, the decision to not make his returns public makes Trump especially guarded in the modern political era. Every major-party presidential nominee since Nixon has put out this information, save Ford, who released a summary when he ran in 1976. Hillary Clinton and her husband have put out returns every year since 1977. Even Pence put out 10 years of tax returns this cycle.

Trump is different. And while his campaign has argued that Clinton is secretive in other areas (they’ve demanded that she turn over all of her emails from her time as secretary of state, for example), it’s also true that Trump has now set a precedent of nondisclosure that future candidates can (and will) follow.